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Finding the Fourth Proportional to 1,320.16, 1,979.28 and 858.40

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Solution

The fourth proportional to 1,320.16, 1,979.28 and 858.40 is: 1,286.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,320.16 : 1,979.28 = 858.40 : x
  2. Step 2: Convert to fraction form
    1,320.16/1,979.28 = 858.40/x
  3. Step 3: Cross multiply
    1,320.16x = 1,979.28 × 858.40
  4. Step 4: Simplify right side
    1,320.16x = 1,699,013.95
  5. Step 5: Solve for x
    x = 1,699,013.95/1,320.16
  6. Step 6: Final answer
    x = 1,286.98

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.